Self-centering foot for sewing machines

ABSTRACT

The present invention comprises a pressure foot assembly operable to resiliently urge layers of fabric downwardly against a feed dog assembly of a sewing machine and which may be urged rearwardly in response to layers of fabric tending to gather or &#39;&#39;&#39;&#39;pucker&#39;&#39;&#39;&#39; therebetween. The pressure foot assembly of this invention is operable to be instantaneously lifted from the layers of fabric in response to movement of the needle shaft operation and, thereby, tends to avoid stretching fabric and layers of fabric advanced between the pressure foot assembly of this invention and a feed dog assembly. In order to maintain a substantially uniform pressure upon layers of fabric being advanced through the machine, a holding foot assembly is provided to resiliently urge downwardly against layers of fabric during the instantaneous lifting of the pressure foot assembly, and to be raised upwardly out of engagement with layers of fabric in response to movement of the needle bar shaft alternately with the pressure foot assembly, the pressure foot assembly and the holding foot assembly being operable to permit sewing of stretchable elastic fabrics without stretching the respective layers. The holding foot assembly is juxtapositioned so as not to coact with the feed dog assembly.

[111 3,759,2e2 1 Sept. 18', 1973 Elite States atet m1 Jean-Blane [57] ABSTRACT.

resent invention comprises a pressure foot assem- SELF-CENTERING FOOT FOR SEWING MACHINES The p erable to resiliently urge layers of fabric downr m a e r d e g r u e .0 Y a m h .w h Di O Vl l n bwa Ferdinand H. Jean-Blane, 2719 N. Thirty-Sixth St., Boise, Idaho 83709 1 7 9 1 a1 2 t c O n 0 m: d e 1 MP 2 72.

tween. The pressure foot assembly of this invention is [21] Appl. No.: 191,298

operable to be instantaneously lifted from the layers of movement of the needle shaft optends to avoid stretching fabric and layers of fabric advanced between the pressure v a mm om Wu m m n mm mm 98 3m Q92 n 6 1%3 mmh I. "Cl C10 d td UhF 1]] 218 555 [.11.

foot assembly of this invention and a feed dog assembly. In order to maintain a substantially uniform pressure upon layers of fabric being advanced through the machine, a holdin References (Iited UNITED STATES PATENTS g foot assembly is provided to resiliently urge downwardly against layers of fabric during the instantaneous lifting of the pressure foot assembly,

and to be raised upwardly out of engagement with layers of fabric in response to movement of the needle bar shaft alternately with the pressure foot assembly, the pressure foot assembly and the holding foot assembly being operable to permit sewing of stretchable elastic Primary Examiner jordan Franklin fabrics without stretching the respective layers. The Assistant Examiner-Peter Nerbun Attorney-John W. Kraft holding foot assembly is juxtapositioned so as not to coact with the feed dog assembly.

4 Claims, 3 Drawing Figures PAIENTED SEN 8 I973 snuzunrz FERDINAND H. JEAN BLANC INVENTOR.

FERDINAND H. J AN BLANC INVENTOR BYXZ/W SELF-CENTERING FOOT FOR SEWING MACHINES FIELD OF INVENTION The present invention relates to a sewing machine pressure foot and more particularly to a self-centering foot for sewing machines operable to uniformly feed fabrics, particularly fabrics including stretchable and elastic materials.

DESCRIPTION OF THE PRIOR ART Sewing machines commonly known in the art generally include a fabric feeding mechanism having a feed dog which is alternately raised and lowered, above and below, a work table plate to sequentially advance the fabric being sewn; and a pressure foot operable to press layers of fabric together against the work table plate and opposingly urge the pressure foot and the layers of fabric therebeneath against the feed dog in its raised position above the work table plate. It is common practice to provide means operable to exert a substantially constant urging force on the foot and consequently on the layers of fabric between the foot and the work table plate and feed dog mechanism, it being understood that such means must be resiliently responsive to the upward movement of the feed dog means. Forces acting upon the foot may result in an upward overthrow of the foot in response to the upward movement of the feed dog, wherein the foot will not be uniformly and constantly urged against the layer of fabric during fabric advance work sequence of the feed dog. Hence, layers of fabric may tend to gather and pucker as they are being stitched in the sewing operation of the machine.

Other considerations, than that of uniformly and constantly urging layers of fabric against the work table plate and the feed dog assembly, must be made for the movement of fabrics past the stitching point of a sewing machine. For example, there are considerations of sewing dissimilar fabrics, one of which may be smoothly textured and be engaged by the feed dog, and one of which may be coursely textured and be engaged by the pressure foot. In the prior art, means of adjustment of the resilient urging means upon the pressure foot have made possible that production of flat, wrinkle-free, sewn fabrics of both similar and dissimilar surface textures. However, such means are inadequate to provide uniform sewing of layers of fabric which are stretchably elastic in character, since the feed dog in advancing the elastic material tends to cause the fabric to stretch under the pressure of the footand the fabric tends to be prevented from being returned to its normal state.

Accordingly, it is an extremely important object of the present invention to provide means urging a pressure foot of a sewing machine operable to permit stretchable elastic fabric to be returned to its normal state, which includes an assembly having simple parts requiring minimum accurate tolerance between the tween fabric layers having different textures, thereby providing uniform advance of fabrics through the machine without gathering or puckering of respective layers of fabric.

These and other objects shall become apparent from the description following, it being understood that modifications may be made without affecting the teachings of the invention here set out.

SUMMARY OF THE INVENTION Generally, the present invention comprises a pressure foot assembly operable to resiliently urge layers of fabric downwardly against a feed dog assembly of a sewing machine and which may be urged rearwardly in response to layers of fabric tending to gather or pucker" therebetween. The pressure foot assembly of this invention is operable to be instantaneously lifted from the layers of fabric in response to movement of the needle shaft operation and, thereby, tends to avoid stretching fabric and layers of fabric advanced between the pressure foot assembly of this invention and a feed dog assembly. In order to maintain a substantially uniform pressure upon layers of fabric being advanced 0 through the machine, a holding foot assembly is provided to resiliently urge downwardly against layers of fabric during the instantaneous lifting of the pressure foot assembly, and to be raised upwardly out of engagement with layers of fabric in resonse to movement of the needle bar shaft alternately with the pressure foot assembly, the pressure foot assembly and the holding foot assembly being operable to permit sewing of stretchable elastic fabrics without stretching the respective layers. The holding foot assembly is juxtapositioned so as not to coact with the feed dog assembly. A more thorough and comprehensive understanding may be had from the detailed description of the preferred embodiment when read in connection with the drawings forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS self-centering foot assembly of this invention before assembly, for illustrative purposes.

FIG. 3 is a cross-sectional side elevational view of the foot portion of a further embodiment of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and more particularly to the FIG. 1, the self-centering foot of the present invention .is shown toadvantage in the environment of a commonly known sewing machine, generally identified by the numeral 10. The sewing machine 10 includes a housing 11 disposed above a work table 12 having an opening 13 covered by a work table plate 14 formed with slots 15 through which a feed dog assembly 16 may be moved reciprocatingly upwardly and downwardly to advance layers of fabric through the machine as hereinafter later described. The feed dog assembly 16 is provided with fabric engaging portion 17 carried by a feed bar 18. One of the terminal ends of the bar 18 is hiiigedly mounted on a rocker arm link 19 suitably fastened to an oscillating feed advance shaft 20 operable to reciprocatingly drive the bar 18 carrying the fabric engaging portion 17 forwardly and rearwardly. The

opposite terminal end of the bar 18 is hingedly fastened to a link 21 pivotally connected to a eamming arm 22 of an oscillating feed lift shaft 23 operable to impart upward and downward movement to the feed dog assembly 16. The combination of upward and downward movement with the forward and rearward movements of the fabric engaging portion 17 tends to create an orbital movement of the fabric engaging portion 17 to advance fabric in the machine as indicated by the arrow in the FIG. 1.

The work table plate 14 includes an entranceway (not shown) for upward and downward reciprocating passage of a needle 24 therethrough with respect to the work table 12. The needle 24 is carried by a needle bar assembly 25 slidably mounted in a bushing 26 in the frame 11, the frame 11 being cantilevered over the work table 12. The needle bar assembly 25 comprises a shaft 27 having a needle chuck 28 carried at one of its terminal ends being operable to hold the needle 24, and a reciprocatingly driven arm means 29 engaging the opposite terminal end of the shaft 27.

Rectilinearly aft of the needle bar assembly 25 in the frame 11 is a pressure foot assembly 30 slidably carried in a bushing 31 mounted in the frame 11. In order to avoid descriptive redundancy, the pressure foot assembly 30, here taught, may be conveniently divided into a pressure bar subassembly 32 and a holding foot subassembly 32'.

Referring now to the FIG. 2, the pressure bar subassembly 32 comprises an upstanding shaft 33 having a foot-centering portion 34, a pivot shaft 35, a presser foot 36 mounted at one of the terminal ends thereof, a mounting block 37, a lifter guide 38, a shaft lifter 39,

'and pressure foot assembly eccentric lever arm 40. The

shaft 33 is provided with a guide slot 38' in the sidewall of the shaft 33 at the end opposite the foot-centering portion 34. The shaft 33 is slidably mounted in the bushing 31 in the frame 11 distally from the terminal end adjacent the centering portion 34 through holes 41 and 41 in the lifter guide 38, through a hole 42 in the mounting block 37, and through a hole 43 in the uppermost portion of the frame 11 opposite the bushing 31, as shown to advantage in the exploded assembly view of the FIG. 2. The shaft 33 may be maintained in alignment and juxtapositioned by a screw 44 threadably carried in the frame 11 and slidably engageable with the slot 38' in the shaft 33. The mounting block 37 may be distally mounted on the shaft 33 and suitably fastened thereto by a screw, such as shown at 45. The lifter guide 38 is disposed on the shaft 33 between the mounting block 37 and the bushing 31, the mounting block 37 and the lifter guide 38 being carried by the eccentric lever arm 40 pivotally mounted in the frame 11. The pressure foot assembly 30, inclding he preer bar subassembly 32 and the holding foot subassembly 32, may be moved upwardly and downwardly with respect to the work table 12 in response to the movement of the eccentric lever arm 40. A spring 46 may be disposed on the shaft 33 between the frame 11 and the mounting block 37 to resiliently urge the presser bar subassembly 32 downwardly toward the work table 12.

Referring now .to the FIG. 3, the centering portion 34 comprises a substantially tubular body portion 47 having a bifurcated rounded terminal end portion 47 being arcuately configured from front to rear in alignment with the presser foot 36, an urging means including a pivot means such as ball-like centering means 48,

a spring 49, and a set screw 50. The pivot shaft 35 includes a transverse rectilinear substantially V-shaped portion, or detent portion, in the terminal end thereof engageable with the ball 48 and is adapted to engage the bifurcated portion 47. The pivot shaft 35 is hingedly mounted to the centering portion 34, such as by pin 51. The pivot shaft 35 includes an upstanding rectilinear substantially V-shaped portion. Similarly the foot 36 is hingedly mounted on the pivot shaft 35, such as by pin 52. It has been found in practice that layers of fabric, tending to gather or bunch in front of the foot, tend to urge the foot 36 rearwardly, and, in so doing, tend not to be stretched by the coacting of the foot 36 and the feed assembly 16. It has also been found that, if the foot 36 tends to remain juxtapositioned rearwardly by the fabric, subsequent advance of the fabric tends to cause the fabric to be stretched.

The FIG. 1 advantageously shows the substantially S-shaped shaft lifter 39 disposed between the lifter guide 38 and the bushing 31 in the frame 11. The shaft lifter 39 is bifurcated at each of its respective ends; and the respective ends are adapted to be juxtapositioned about the shaft 33 of the pressure foot assembly 30 and the needle bar assembly 25. An operating block 53 is selectively juxtapositioned, and is suitably fastened to the needle bar shaft 27, such as by the screw 54. In the downward movement of the needle bar shaft 27, the block 53 impinges the shaft lifter 39, moving it downwardly, causing the opposite bifurcated end to move the lifter guide 38 and, consequently, the presser bar subassembly 32 carried by the shaft 33 upwardly. Hence the foot 36 is caused to be raised upwardly with respect to the work table 12 and off of layers of fabric disposed therebetween, at which time the foot 36 is urged to its normal centering position by the spring 49 and the ball 48 coacting on the transverse detent portion of the pivot shaft 35. As a result, fabric advanced through the machine in the manner hereinbefore described tends not to be stretched.

In practice it has been found to advantage to maintain uniform pressure upon the layers of fabric to induce uniform advance of the fabric through the machine. Therefore, the further subassembly of a holding foot 32' may that provided,.although it is to be understood thate the holding foot assembly 32' is not required with all types of fabrics, and that the selfcentering pressure foot assembly 30 may be used with some fabrics without the holding foot 32'.

The holding foot subassembly 32' comprises a substantially L-shaped bar 55 carried by the operating block 53 on the needle bar shaft 27, and a foot 56 suitably fastened to the bar 55. The bar 55 is mounted in a bushing (not shown) in the frame 11. A spring 57 is disposed on the needle bar shaft 27 between the bar 55 and the driven arm means 29 of the needle bar assembly 25 to resiliently urge the holding foot assembly 32' downwardly with respect to the working table 12. When the neede bar shaft 27 is reciprocatingly moved upwardly, the operating block 53 impinges the bar 55 to lift the foot upwardly with respect to the table 12. It may be understood that the presser assembly 32 and the holding foot assembly 32' may be alternately raised with respect to the work table 12 during the advance of layers of fabric through the machine, and may both be selectively raised together in response to movement of the eccentric lever arm 40 as hereinafter described. The bar 55 is provided with a shoulder portion 58,

shown to advantage in the FIG. 2. The portion 58 is adapted to be carried by projections 59 and 59' provided on mounting block 37.

Referring now more particularly to the FIG. 2, the presser foot 36 is provided with projections 60 and 60 through which the needle 24 may pass in its reciprocating travel. The foot 56 may be suitably mounted to the bar 55 such as by screw 61, at one of its terminal ends. The opposite terminal end of the foot 56 comprises a substantially rectangular shoe portion 62 having an opening 63 therein. The shoe portion 62 is juxtapositioned between the projections 60 and 60' of the presser foot 36 and disposed so that the needle 24 may reciprocatingly pass through the opening 63 of the shoe in operation the shoe 62 tends to urge layers of fabric resiliently downwardly with respect to the table 12, while the pressure foot 36 tends to coact against the feed dog advance assembly 16. That is to say that in practice it has been found to advantage to juxtaposition the shoe 62 between fabric engaging portions 17 of the feed dog advance assembly 16 because, while substantial uniform resilient downward pressure is maintained on the fabric, the shoe 62 being between the fabric engaging portions 17 tends not to cause the layers of fabric to be stretched therebetween.

Having thus described in detail a preferred apparatus which embodies the concepts and principles of the invention and which accomplishes the various objects, purposes and aims thereof, it is to be appreciated and will be apparent to those skilled in the art that many physical changes could be made in the apparatus without altering the inventive concepts and principles embodied therein. Hence, it is intended that the scope of the invention be limited only to the extent indicated in the appended claims.

1 claim:

1. in a pressure foot for sewing machines, the combination of an upstanding shaft slidably carried by the housing of a sewing machine, mounting means on said shaft mounting said shaft in said housing, urging means on one of the ends of said shaft disposed between said mounting means and said sewing machine housing operable to resiliently urge said shaft downwardly with respect to the work table of said sewing machine, said shaft including a foot-centering means at the terminal end of said shaft opposite said urging means, a pressure foot assembly including an upstanding pivot shaft portion carried by said foot-centering means and a presser foot pivotally mounted at one of the terminal ends of said upstanding pivot shaft, said presser foot being normally in engagement with fabric being sewn by said sewing machine, a shaft lifter means in communication with said mounting means on said upstanding pivot shaft and the needle bar shaft of said sewing machine, said shaft lifter means being operable to lift upwardly said upstanding pivot shaft including said pressure foot assembly in response to movement of said needle bar shaft, said foot-centering means including a tubular shaft body, said shaft body being rounded and bifurcated at one of its terminal ends, said upstanding pivot shaft including an upstanding projection pivotally carried between said shaft body bifurcated ends, means pivotally mounting said upstanding pibot shaft in said shaft body, said upstanding projection being rectilinearly substantially V-shaped, a ball-like centering means in said shaft body, means urging said centering means against said substantially V-shaped upstanding projection of said upstanding pivot shaft, said centering means being operable to urge said upstanding pivot shaft toward the lowermost invert portion of said V- shaped upstanding projection to tend to normally center said upstanding pivot shaft and said presser foot carried thereby to permit said pressure foot assembly to be moved rearwardly in response to movement of fabric therebeneath and to return said foot to its normal position when said pressure foot assembly is lifted upwardly.

2. The apparatus of claim 1 in which said mounting means comprises an eccentric shaft lifting camming lever arm joumaled for rotation in said sewing machine housing, a mounting block suitably fastened on said shaft adjacent said urging means, a substantially U- shaped lifter guide carried on said shaft, said lifter guide having an outwardly projecting portion carried by said camming lever, said lifter guide projecting portion being disposed between said camming lever and said mounting block, said shaft being operable to be selectively lifted upwardly and downwardly in response to rotation of said camming lever on said projecting portion, said lifter guide being carried by said shaft lifter.

3. The apparatus of claim 1 in which said shaft lifter comprises a substantially S-shaped member having a first bifurcated portion juxtapositioned on said shaft and a second bifurcated portion juxtapositioned on said sewing machine needle bar shaft, and an operating block selectively mounted on said sewing machine needle bar shaft, said operating block being operable to impinge said shaft lifter in response to movement of said sewing machine needle bar shaft.

4. The apparatus of claim 3 including a holding foot assembly comprising a substantially L-shaped bar having a bifurcated portion juxtapositioned about said sewing machine needle bar shaft, said bifurcated portion being carried by said operating block, said bar being slidably engageable with said mounting block on said pressure foot shaft, an upstanding holding foot being suitably mounted at one of the terminal ends of said bar and juxtapositioned in said presser foot, said operating block being adapted to impinge said bifurcated portion of said bar in response to the upward movement of said sewing machine needle bar shaft and to movesaid holding foot assembly upwardly, and to impinge said shaft lifter in response to the downward movement of said sewing machine needle bar shaft to lift said pressure foot assembly, said holding foot assembly and said pressure foot ssembly being operable to be lifted alternately at different times.

t a a a a 

1. In a pressure foot for sewing machines, the combination of an upstanding shaft slidably carried by the housing of a sewing machine, mounting means on said shaft mounting said shaft in said housing, urging means on one of the ends of said shaft disposed between said mounting means and said sewing machine housing operable to resiliently urge said shaft downwardly with respect to the work table of said sewing machine, said shaft including a foot-centering means at the terminal end of said shaft opposite said urging means, a pressure foot assembly including an upstanding pivot shaft portion carried by said foot-centering means and a presser foot pivotally mounted at one of the terminal ends of said upstanding pivot shaft, said presser foot being normally in engagement with fabric being sewn by said sewing machine, a shaft lifter means in communication with said mounting means on said upstanding pivot shaft and the needle bar shaft of said sewing machine, said shaft lifter means being operable to lift upwardly said upstanding pivot shaft including said pressure foot assembly in response to movement of said needle bar shaft, said foot-centering means including a tubular shaft body, said shaft body being rounded and bifurcated at one of its terminal ends, said upstanding pivot shaft including an upstanding projection pivotally carried between said shaft body bifurcated ends, means pivotally mounting said upstanding pibot shaft in said shaft body, said upstanding projection being rectilinearly substantially V-shaped, a ball-like centering means in said shaft body, means urging said centering means against said substantially V-shaped upstanding projection of said upstanding pivot shaft, said centering means being operable to urge said upstanding pivot shaft toward the lowermost invert portion of said V-shaped upstanding projection to tend to normally center said upstanding pivot shaft and said presser foot carried thereby to permit said pressure foot assembly to be moved rearwardly in response to movement of fabric therebeneath and to return said foot to its normal position when said pressure foot assembly is lifted upwardly.
 2. The apparatus of claim 1 in which said mounting means comprises an eccentric shaft lifting camming lever arm journaled for rotation in said sewing machine housing, a mounting block suitably fastened on said shaft adjacent said urging means, a substantially U-shaped lifter guide carried on said shaft, said lifter guide having an outwardly projecting portion carried by said camming lever, said lifter guide projecting portion being disposed between said camming lever and said mounting block, said shaft being operable to be selectively lifted upwardly aNd downwardly in response to rotation of said camming lever on said projecting portion, said lifter guide being carried by said shaft lifter.
 3. The apparatus of claim 1 in which said shaft lifter comprises a substantially S-shaped member having a first bifurcated portion juxtapositioned on said shaft and a second bifurcated portion juxtapositioned on said sewing machine needle bar shaft, and an operating block selectively mounted on said sewing machine needle bar shaft, said operating block being operable to impinge said shaft lifter in response to movement of said sewing machine needle bar shaft.
 4. The apparatus of claim 3 including a holding foot assembly comprising a substantially L-shaped bar having a bifurcated portion juxtapositioned about said sewing machine needle bar shaft, said bifurcated portion being carried by said operating block, said bar being slidably engageable with said mounting block on said pressure foot shaft, an upstanding holding foot being suitably mounted at one of the terminal ends of said bar and juxtapositioned in said presser foot, said operating block being adapted to impinge said bifurcated portion of said bar in response to the upward movement of said sewing machine needle bar shaft and to move said holding foot assembly upwardly, and to impinge said shaft lifter in response to the downward movement of said sewing machine needle bar shaft to lift said pressure foot assembly, said holding foot assembly and said pressure foot ssembly being operable to be lifted alternately at different times. 